This application claims the priority of German application 197 18 203.8, filed Apr. 30, 1997, the disclosure of which is expressly incorporated by reference herein.
The present invention relates to an air bag curtain for a vehicle window and the like, and more particularly, to an air bag curtain having several tube-shaped chambers which are arranged side-by-side, are spaced from one another and can be filled with gas and which have a largely circular cross-section after they are filled with gas.
DE 22 22 621 A1 describes an air bag curtain which can be filled with gas and in which, by way of a linear connection of the two curtain sections disposed on one another, gas-fillable tube shaped chambers are constructed. In the gas-filled effective position, the chambers have largely the same circular cross-section along its longitudinal course. As a result, a maximal energy absorption capacity exists when loaded by the occupants. A fixing of the air bag curtain in its effective position so that this curtain cannot be displaced from its protective covering position by the impacting occupant was not considered.
A general background of an air bag which is held in its effective position by additional holding devices is also found in DE 43 07 175 A1; DE 42 38 427 A1; DE 92 11 423 U1; and DE 41 37 749 A1.
An object of the present invention to hold an air bag curtain in a gas-filled manner in an effective securely protective position thereof.
This object has been achieved in accordance with the present invention by providing that in the effective position, in a gas-filled manner, the air bag curtain extends between two lateral fastening points, and in that the chambers, which are crossed by a tension line connecting the two fastening points with one another are each constructed with a bulging in the crossing area which results in an oval cross-section oriented approximately in the direction of the tension line.
An air bag curtain in accordance with the present invention is normally disposed in a gathered, stored manner along an edge of the vehicle window and is filled during the crash by the gas from an activated gas generator or gas accumulator. Thereby, the air bag is changed into its effective position in front of the vehicle window. The air bag can also be arranged, however, on the inside at the roof in the transverse direction of the vehicle and spread out in front of an occupant. That is, the air bag curtain, which in contrast to a single-chamber air bag, has individual, mutually gastightly separated chambers, has the advantage that the air bag curtain can be filled with a lower gas quantity which, in the event of a side impact, can be achieved particularly advantageously within a shorter time period and, because of the lower gas pressure, in a more protective manner for the occupant. Consequently, a circular gas-filled cross-section resulting from the boundary lines of a chamber leads to a maximal energy absorption capacity when the chambers are loaded by the occupants.
So that the air bag cannot be displaced from its effective position in the vehicle interior in front of the vehicle window by the impacting occupant, the curtain sides are fastened on the vehicle body and the interior panelling of the vehicle so that the gas filling of the chambers creates a tension line between the fastening points on both sides. The air bag curtain is thereby tensioned between the fastening points and is held close to the vehicle window.
On this tension line, the chambers are constructed with a larger width because of the course of the boundary lines bounding the chambers. Consequently, an oval cross-section of the chambers in the direction of the curtain surface is formed in this area by which a higher tension force can be generated between the fastening points without imparing the circular cross-sectional shape of the adjoining chamber areas.
This individual construction of the chambers results in an optimal energy consumption being maintained in the impact area of the occupant as the result of the circular cross-sectional shape of each chamber. A maximal tension can nevertheless be introduced into the air bag curtain along the tension line by way of which the air bag curtain is securely held in its effective position.
The effective position of the air bag curtain can be fixed in a particularly secure manner if the tension line is provided to extend below the point of gravity of the head of a sitting occupant. The shaping boundary lines of the chambers can easily be produced by a sewing or weaving together of the two opposite air bag walls.